USGS Streamgage 11051500
Santa Ana River near Mentone, CA
Santa Ana River near Mentone, CA is USGS streamgage 11051500 in California, monitoring river discharge in hydrologic subbasin 18070203. It drains a watershed of about 210 square miles. Discharge records at this site go back to 1891. Typical flow runs near 1.9 cfs in July and 19.3 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 210 sq mi
- Gauge elevation
- 1,950 ft
- Subbasin (HUC-8)
- 18070203
- Coordinates
- 34.10834, -117.10059
- USGS site number
- 11051500
- Records begin
- 1891-02-23 (135 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 130 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.
| Month | Low p10 | Typical p50 | High p90 | Range |
|---|---|---|---|---|
| January | 0 | 4.2 | 82.6 | |
| February | 0.7 | 8.2 | 176 | |
| March | 1 | 12.7 | 247 | |
| April | 0.8 | 19.3 | 228.2 | |
| May | 0.4 | 7.2 | 168.2 | |
| June | 0.1 | 2.5 | 96.9 | |
| July | 0 | 1.9 | 60.9 | |
| August | 0 | 1.5 | 36 | |
| September | 0 | 1.2 | 27.7 | |
| October | 0 | 1.3 | 30.4 | |
| November | 0 | 1.8 | 24 | |
| December | 0 | 3 | 37.7 |
All values in cubic feet per second (cfs).
Common questions
- When does Santa Ana River near Mentone, CA normally run highest?
- April, on the long-term record. The median daily flow that month is about 19.3 cfs, against 1.2 cfs in September, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for Santa Ana River near Mentone, CA?
- It depends on the month. In January, half of days historically fall near 4.2 cfs, with the middle 80% of days between 0 and 82.6 cfs. The month-by-month table on this page gives the full range.
- How long has Santa Ana River near Mentone, CA been measured?
- Discharge records at USGS site 11051500 begin in 1891, about 135 years, covering roughly 9,125 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is Santa Ana River near Mentone, CA?
- The gauge sits at 34.10834, -117.10059, in California, in hydrologic subbasin 18070203, at an elevation of about 1,950 feet, draining roughly 210 square miles.
- Can I use Santa Ana River near Mentone, CA data for flood or safety decisions?
- No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.